Precision low-dose, low-waste syringes and ergonomic attachments therefor

ABSTRACT

Precision low-dose, low-waste syringe configurations have a reduced diameter lumen for dispensing 0.01 ml increments of contents. Plunger and lumen configurations and a needle interface eliminate dead space. Ergonomic attachments improve the control and precision of delivery of syringes. An attachment main body includes a gripping surface to permit a user to engage the attachment and move the attachment main body, and thus the syringe plunger relative to the syringe barrel using sliding movement. Optical enhancement features are provided on the attachment to improve the readability of gradations and plunger position. The attachment may be provided with an assist feature, which may be a traction wheel mounted on the attachment body. An alternative configuration suitable for syringe contents of higher viscosity may include a pair of toothed pinion gears on a wheel and which cooperate with respective toothed racks formed on or fastened to the syringe body.

This application is a continuation of application Ser. No. 16/120,122 filed on Aug. 31, 2018, titled PRECISION LOW-DOSE, LOW-WASTE SYRINGES AND ERGONOMIC ATTACHMENTS THEREFOR, which claims priority to provisional application Ser. No. 62/686,915, filed on Jun. 19, 2018. The subject matter of these applications is hereby incorporated herein by reference in its entirety.

FIELD

The disclosure relates generally to medical devices, including syringes for controlling delivery of medications and biological fluids to a patient. The disclosure also relates to syringe configurations that facilitate precise delivery of very small volumes and/or doses and low waste of syringe contents. The disclosure relates further to attachments and adapters for improving the ergonomics of syringe operation and for enabling a user to precisely control the actuation of a syringe.

BACKGROUND

In some areas of medicine, there is trend towards lower volume, higher concentration dosages of therapeutic compounds and drugs to be delivered via injection, typically by syringe. For example, in the cosmetic surgery field, recent trends include procedures termed “High Dose Micro-focused” or “HDMF” injections of botulinum toxin, which may involve the use of high concentration and relatively small delivered volumes of compounds or mixtures compared to the concentrations and volumes that have, in the past, been typically used for such injections in cosmetic treatments and in very precise amounts and in very focused, localized areas of the human face and body. The cost of these compounds and mixtures are relatively high to begin with. As the concentrations increase, the relative cost of wasted amounts of the compounds and mixtures also increases.

A number of problems in the prior art stem from the limitations of existing syringes to be adapted to precision, low dose/volume applications. For example, the ability to deliver precise volumes in increments of as small as 0.01 ml may typically be required in such applications. Existing syringe configurations are not readily adapted to precise control of delivery such small increments. A related problem is accurate control and reading of syringes as the form factor becomes reduced. Still another problem is that prior art syringe configurations may demonstrate structural deficiencies when their form factor is reduced. More specifically, for example, reducing the plunger diameter significantly to fit within a reduced syringe lumen may render the plunger susceptible to buckling or bending when a force is applied, thus affecting syringe function and accuracy. Ergonomic factors, including user comfort and control and readability of syringe indicia and plunger position also become a factor as the lumen diameter and other parameters are reduced.

Yet another problem is the need to reduce wasted residual amounts left undelivered in the “dead space” of prior art syringes, as the concentration of expensive substances, such as botulinum toxin in a delivery medium (solvent) increases, the cost of wasted amounts of the mixture also increases. Another problem relates to the structural shortcomings of traditional syringes when their form factor is reduced in size.

Yet another problem is the need for precise control of the dispensing of syringe contents, such as dermal fillers and other compositions that may be of a relatively high viscosity.

It would therefore be advantageous to provide devices, including syringes and attachments that address the aforementioned shortcoming and others in the prior art.

SUMMARY

According to one aspect of the disclosure, precision low-dose, low-waste syringe configurations are provided for facilitating precise control and delivery of syringe contents and for reducing or eliminating residual waste. The syringe configurations may have a reduced diameter lumen such that a relatively long travel of the syringe plunger is undertaken for dispensing a given volume of syringe contents, which improves the precision with which contents can be dispensed. Total syringe volume may be on the order of 0.25 or 0.50 milliliters.

According to another aspect of the disclosure, an ergonomic attachment is provided for improving the control and precision of delivery of syringes. The attachment may be used with syringes such as the low-dose, low-waste syringes described herein, or may be used with known traditional prior art syringes to improve the precision and control thereof. A main body extends axially to a plunger engaging end and a syringe guide end. The plunger engaging end may include a receptacle for receiving a thumb pad on the end of the syringe plunger. The guide end includes a guide, which provides for sliding engagement with the syringe barrel. The main body includes a gripping surface to permit a user to engage the attachment with his or her fingers or thumb and to move the attachment main body, and thus the syringe plunger, relative to the syringe barrel using sliding movement between the user's thumb and fingers. This mode of actuation provides improved control of the syringe, enables the user to grip the syringe closer to the injection point (needle end), provides stability to the syringe plunger, and provides more accurate control of the delivery of syringe contents.

According to a further aspect, a syringe attachment is provided with an assist feature, which may be a traction wheel mounted on the attachment body. The traction wheel may provide a mechanical advantage, i.e., leverage, to enable the user to move the attachment body, and thus the syringe plunger, with high precision. A number of wheel mounting slots may be provided on the attachment body to enable a user to select a comfortable position. The attachment may be provided as a kit including a number of wheels of various sizes to enable a user to configure the attachment according to their preference for comfort and control. The wheel may be mounted for selective engagement with the syringe barrel. In one configuration, the main body may flex to permit the wheel to engage the syringe barrel when pressure is applied by the user's thumb. In another configuration, the wheel may be biased in an unengaged position using springs or resilient elements in the mounting slots.

According to another aspect, an attachment is provided with features for generating audible or tactile indications to a user of a precise incremental dose. A syringe body may be provided with raised gradations formed therein and on a surface that is engaged by an assist feature on the attachment. When the assist feature is rolled over each raised portion, the user senses the tactile event and perceives that the syringe plunger has moved one increment. Thus, more precise indication and control is facilitated for even small movements of the syringe plunger.

According to another aspect, optical enhancement features are provided to improve the readability of gradations and plunger position. Small gradations indicating incremental doses of as small as 0.01 ml may be provided on the syringe barrel. A magnifying element, such as a prism or lens, may be incorporated into the attachment near the syringe guide end. A reference sight, which may be hairline indicator incorporated into the attachment and/or magnifying element, may be provided on the attachment guide end to indicate the position of the attachment, and thus the plunger and plunger end, relative to the gradations on the syringe barrel. In this manner, very fine gradations may be indicated on the syringe barrel and can be read in combination with the plunger position to indicate very small incremental movements of the plunger.

According to a further aspect, syringes are provided which have particular suitability to low dosage applications. Overall syringe volumes of 0.25 ml or 0.50 ml require small lumen diameters and small plunger diameters. The syringe barrel may be provided with gradations corresponding to 0.01 ml incremental doses, resulting in 25 gradations on the 0.25 ml configuration and 50 gradations on the 0.50 ml syringe. The syringes may be provided with a thickened wall to facilitate handling and control. A flat portion on the syringe barrel improves the readability of the gradations and viewing of the syringe contents and plunger piston as well as operation with optical enhancements on an attachment that may contain an assist feature that facilitates precise control of the plunger movement.

According to another aspect, syringe plunger configurations and needle hub/syringe interfaces with eliminated dead space. A lumen end wall extends into abutting engagement with an end surface of a needle hub. The plunger piston is provided with a flat surface such that the lumen is entire evacuated when the plunger is in its fully inserted position and no waste material remains except in the small needle lumen. This results in cost savings.

DESCRIPTION OF THE DRAWINGS

The above and other attendant advantages and features of the invention will be apparent from the following detailed description together with the accompanying drawings, in which like reference numerals represent like elements throughout. It will be understood that the description and embodiments are intended as illustrative examples according to aspects of the disclosure and are not intended to be limiting to the scope of invention, which is set forth in the claims appended hereto.

FIG. 1 is a perspective view of an example attachment, according to aspects of the disclosure, assembled on a syringe, according to aspects of the disclosure.

FIG. 2A is an exploded view of the attachment and syringe combination of FIG. 1 . FIG. 2B is a detail view of a portion of FIG. 2A, as indicated.

FIG. 3 is a perspective view of the attachment and syringe combination of FIG. 1 , showing a different position of the attachment and syringe plunger.

FIG. 4 . is a cross-section of the attachment and syringe combination of FIG. 3 in the plane 4-4 in FIG. 3 .

FIG. 5 is a cross-section of the attachment and syringe combination of FIG. 3 in the plane 5-5 in FIG. 3 .

FIG. 6 is a top view of a portion of the attachment and syringe combination of FIG. 3 , showing a magnified view thru an optical element.

FIG. 7 is a perspective of a first alternative attachment configuration assembled on a syringe, the attachment being without an assist feature.

FIGS. 8A and 8B are cross-sections showing an example needle hub/syringe interface and plunger seal advantageous for a syringe having a total volume of about 0.25 ml, with the plunger in a slightly open position and a fully inserted position, respectively.

FIGS. 9A and 9B are cross-sections showing an example needle hub/syringe interface and plunger seal advantageous for a syringe having a total volume of about 0.50 ml, with the plunger in a slightly open position and a fully inserted position, respectively.

FIG. 10 is an exploded view of an attachment and syringe with the attachment having an optical element mounting component that is adjustable.

FIG. 11 is a perspective of second alternative attachment configuration assembled on a syringe.

FIG. 12 is an exploded view of the alternative attachment and syringe combination of FIG. 11 .

FIG. 13 is a detailed perspective of a syringe guide end of the alternative attachment of FIGS. 11 and 12 .

FIG. 14 is a bottom perspective of the attachment and syringe combination of FIG. 11 .

FIG. 15 is a bottom perspective of the attachment of FIG. 11 .

FIG. 16 is a perspective view of a third alternative attachment and syringe combination.

FIG. 17 is a side view of the attachment and syringe combination of FIG. 16 .

DETAILED DESCRIPTION

FIGS. 1 and 2A show an assembled view and an exploded view, respectively, of an example syringe attachment 100 and syringe 200 according to aspects of the disclosure. Attachment 100 may include an elongate main body portion 110, which extends from a syringe plunger engaging end 120 to an opposite syringe guide end 130. Main body portion may include a gripping surface 112 which permits a user to apply a sliding force on the attachment using the fingers and or thumb. Syringe plunger engaging end 120 may include a receptacle or slot 122 for receiving a thumb pad or button 242 of the syringe plunger. An aperture 124 may accommodate the plunger shaft 241. Receptacle 122 and/or aperture 124 may be sized to provide a friction fit around thumb pad 242 and plunger shaft 241 to firmly retain the plunger relative to the attachment 100. FIG. 5 is a cross section that further illustrates an example orientation of the syringe button 242 within the syringe plunger engaging end 120 of attachment. Syringe guide end 130 may include a generally U-shaped syringe guide 135 that is shaped complementarily to the outer surface of the syringe barrel 210 and includes an inner surface 136 that facilitates sliding movement along the syringe barrel 210. Surface 136 may be provided with a friction reducing coating, lubricant or surface texture. A pair of opposed retaining edges 138 may be formed in the guide end 130 to engage a flat portion of the syringe barrel to keep the attachment aligned with the syringe barrel (and plunger) axis and prevent lateral and upward movement of the syringe barrel 210 within the guide 135.

According to aspects of the disclosure, syringe 200 includes features for facilitating the storage and delivery of very small incremental doses, including with a small diameter lumen, plunger diameter and plunger seal, while having an external form, i.e., outside diameter that facilitates easy handling. In this regard the barrel walls may be of increased thickness compared to prior art syringe configurations. Syringe barrel 210 may be provided with an internal lumen diameter that provides a total syringe volume of about 0.50 ml, with 50 gradations indicated on the syringe barrel, or in another configuration, about 0.25 ml, with 25 gradations indicated on the syringe barrel. With a syringe length of 4 inches with a 0.50 ml volume and 50 gradations, for example, each incremental 0.01 ml dose may require a controlled a plunger movement on the order of 0.08 inches. As will be appreciated by those of ordinary skill, the features of the syringe and attachments described above and further below herein will facilitate the small, precise and controlled movements of the syringe plunger for such small incremental doses.

Still referring to FIGS. 1 and 2A, syringe 200 may include a plunger receiving end 230 having a flange 231 extending therefrom, for permitting traditional operation of the syringe 200 using two fingers, one on each side of flange 231, and the thumb on syringe thumb pad 242. The flange 231 may include a recessed portion 232 to accommodate the width of attachment 100. The syringe wall thickness and material are chosen to provide a view of the syringe plunger piston 250.1 within the lumen as viewed thru the flat portion 211 of the syringe barrel 200. A needle receiving end 220 of the syringe may engage a needle hub 260 in a manner that will be described later herein.

According to another aspect of the disclosure, the attachment 100 may be provided with an assist feature 140 to enhance control of the movement of attachment 100, and thus movement of the syringe plunger 241 and piston 250.1 relative to the syringe barrel 200. Assist feature 140 may be provided in the form of a traction wheel, which may include a rubberized outer member 142 mounted on an inner hub 144. Hub 144 may include extending axles that are received in slots 114.1 and 114.2 in the attachment main body 110. Assist feature 140 may provide a mechanical advantage or leverage to the user during operation. More specifically, the user may use their thumb and or finger to rotate the assist feature 140 which may selectively and frictionally engage the flat surface 211 of the syringe body 200. The diameter of the assist feature 140 provides leverage to the user and allows the user to move the attachment incrementally using a rolling motion. Referring additionally to FIG. 4 , the assist feature 140 may rest in a disengaged position shown, where it is slightly above and disengaged from the syringe flat surface 211. Selective engagement of the assist feature 140 may be provided by flexibility (deformation) of the main body 110 of the attachment 100. Alternatively, springs or biasing elements may be incorporated into the axles of hub 144 or into the slots 114.1 and 114.2 such that the assist feature 140 engages the surface 211 when a slight downward force is exerted on the assist feature 140 by the user, and disengages the surface 211 when user force is removed. FIG. 3 illustrates the operation of an example syringe/attachment combination and shows a position in which the syringe plunger is fully inserted into the syringe lumen.

According to a further aspect of the disclosure, the attachment and/or syringe may be provided with features that facilitate the tactile sensing of an incremental dose and movement of the syringe plunger. For example, referring to FIG. 2B, the gradation indicia 212 on the syringe barrel flat surface 211 may be provided as raised elements, such as ridges or hashes formed in the syringe barrel and of a suitable dimension such that rolling of the assist feature 140 over each ridge generates a tactile event, such as a slight resistance and/or clicking sound, that can be sensed by the user. As an alternative, assist feature wheel hub 144 may be provided with a sound generator, such as a toothed element and a reed element, that generates a clicking sound for an incremental rotation corresponding to one gradation on the syringe surface.

Referring additionally to FIG. 6 , in accordance with another aspect of the disclosure, attachment 100 may be provided with an optical element 150 to enhance the user's viewing of the syringe plunger piston 250.1 and gradations 212 and thus enhance precision of operation of the syringe. Attachment syringe guide end 130 may include a pair of upwardly extending sidewalls 132, each having a vertical shoulder 134 and lower horizontal shoulder 136 which define a receiving space for the optical element 150. Optical element 150 may be a magnifying prism made of an optically transparent material and having magnification properties. As will be recognized, the optical element 150 moves with the syringe plunger and thus stays oriented above the syringe plunger piston 250.1 as the attachment and plunger move during syringe operation, thus enabling the user to see a magnified view of the plunger piston 250.1 and gradations 212 as syringe contents are dispensed/administered. A reference sight line or reticle 180 may be a hairline element incorporated into or adjacent to the optical element or in the attachment and may provide a precise indication of the syringe plunger piston movement, even in cases where the piston is not entirely visible to the user due to syringe wall thickness or material, for example. As best seen in FIGS. 3 and 4 , a flat bottom surface of optical element 150 rests a small distance above the flat surface 211 of the syringe barrel. As will be recognized, this distance enables an accurate reading of the syringe gradations and plunger movement. Moreover, this distance may be adjusted/selected in order to vary the level of magnification provided by the optical element.

According to yet another aspect of the disclosure, the assist feature and optical enhancement features of the attachment and attachment/syringe combinations contemplated herein include highly customizable aspects. Attachment 100 may include two or more mounting slots 114.1 and 114.2 to permit a user to customize the assist feature position and thus the attachment configuration according to a desired comfort level. In addition, assist features 140 may be provided as a kit of several different sized wheels with the attachment to enable the user to select a desired wheel size to achieve precise control for the user's hand, finger or thumb size or other attribute. Likewise, the optical element 150 is removable and may be fastened with snap elements/detents onto the attachment 100 and a kit of optical elements of various magnification power may be provided to enable customization according to a user's preferences, or the optical element may be removed to permit a user/physician to use an eye loop or magnifying eyeglasses in conjunction with use of the syringe. As will be recognized, the mounting configuration for the assist feature and the optical enhancement feature permits quick refitting of alternative parts.

FIG. 7 illustrates an alternative attachment configuration 700 in which the assist feature is omitted and which facilitates syringe operation using relative lateral (sliding movement) of a user's thumb and fingers. The main body 710 includes a gripping surface 712 to permit a user to engage the attachment with his or her fingers or thumb and to move the attachment main body, and thus the syringe plunger, relative to the syringe barrel using sliding movement between the user's thumb and fingers. This mode of actuation provides improved control of the syringe, enables the user to grip the syringe closer to the injection point (needle end), provides stability to the syringe plunger, and provides more accurate control of the delivery of syringe contents.

According with yet another aspect, the disclosure provides low-waste syringe/needle interfaces and syringe plunger piston configurations. FIGS. 8A and 8B are cross-sections showing an example needle hub/syringe interface and plunger seal advantageous for a syringe having a total volume of about 0.25 ml, with the plunger in a slightly open position and a fully inserted position, respectively. Needle hub 260 includes a needle 262 mounted therein and an end surface 264 with which the end of needle 262 is flush mounted therewith. Needle hub 260 includes an outer threaded base that engages internal threads on the syringe. Syringe 200 includes an internal lumen wall extension 242 that extends into the interior of needle hub 260 and has an end 243 that forms a sealing interface with the hub end surface 264. Syringe plunger piston 250.2 includes an internal space for receiving a barb-like end 245 of plunger 240. Syringe plunger piston 250.2 also includes a flat end surface 252.2. As can be seen with additional reference to FIG. 8B, when the piston is at the full extent of its insert into the syringe lumen, the piston end surface 252.2 is in abutting contact with the end surface 264 of the needle hub, thus eliminating any dead space within the needle hub and thus completely evacuating the syringe contents from the lumen. This may result in significant cost savings for expensive syringe contents. For delivery of syringe contents, needle 262 may be a 30-gauge needle, which is of a small size and mitigates pain and tissue damage during injection. Moreover, one method of operating the device contemplated herein is to utilize a larger (smaller gauge) needle of a standard, low cost configuration, such as a standard 20-gauge needle on the syringe, to facilitate quick retrieval of material (i.e., neurotoxin) into the syringe. Once the syringe is filled, a 30-gauge needle with the low-waste features described herein may be installed on the syringe and used for delivery.

FIGS. 9A and 9B are cross-sections showing an example needle hub/syringe interface and plunger seal advantageous for a syringe having a total volume of about 0.50 ml, with the plunger in a slightly open position and a fully inserted position, respectively. In this configuration, the syringe lumen has an increased diameter compared to the configuration of FIGS. 8A and 8B. The syringe piston 250.1 may include a first portion 253.1 that has a diameter suitable to form a seal with the lumen. The first portion 253.1 may taper down to a smaller diameter portion 254.1 that fits within the interior of the lumen end wall, which may be of a standard dimension to fit a standard needle hub 260.

FIG. 10 is an exploded view of an alternative attachment configuration 1000 showing an alternative optical element mounting arrangement. Attachment guide end 1030 may include a pair of circular mounting tubes 1032 formed therein (one shown in FIG. 10 ) which receive respective mounting rods 1152 of a lens mounting frame 1154. A magnifying lens 1150 may be mounted within the lens mounting frame. This configuration may provide higher magnification of the syringe gradations and reference sight 1080 and may be adjusted to a user's preference.

FIG. 11 is a perspective view of an assembled alternative attachment 1100 and syringe 200 according to alternative attachment configuration 1100. FIG. 12 is an exploded view of the same embodiment. In this embodiment, the magnification element 1150 is oriented differently than in the embodiment of FIG. 1 , with a flat side 1152 of the magnifying element 1150 facing the assist feature 1140. This configuration provides additional clearance for the user's thumb when engaging the assist feature 1140 and provides a viewing angle of the magnified area of the syringe (the area beneath the magnifying element 1150) that may be ergonomically advantageous, i.e., allowing the user to view the magnified areas of the syringe from a direction towards the needle end of the syringe and closer to the area of focus when performing injections.

FIG. 14 is a bottom perspective view of the attachment/syringe combination of FIG. 11 with the attachment in a “zero” position in which the contents of the syringe have been entirely evacuated. As can be seen, the reference sight line or reticle 1180 coincides with the gradation 1402 representing a “zero” or fully emptied position of the syringe. As will be recognized, the “zero” gradation may be positioned in an offset manner from the zero position of the syringe plunger (i.e., when it is bottomed against the end wall of the lumen) such that the reticle 1180 and zero gradation 1402 can indicate the fully emptied position of the attachment precisely to the user. Referring additionally to FIG. 15 , reticle 1180 may include a filament coated with a conspicuous color, such as red, in order to provide a sharp contrast and enable the user to see the precise location of the plunger (and position of the attachment relative to the syringe) when the user views the magnified syringe area within the field of view of the magnifying element 1150. To further enhance viewing and precision, the attachment may include lateral reference shoulders 1182.1 and 1182.2 that coincide with the reference line or reticle 1180 and enable the user to view the position of the reticle 1180 from the sides of the syringe. The reference shoulders 1182.1 and 1182.2 may include a coating in a conspicuous color, such as red, to further define a line of reference on the attachment. As seen in FIG. 14 , the reference shoulder 1182.2 is aligned with the “zero” gradation when the syringe plunger, and thus the attachment, have reached the full extent of their travel relative to the syringe.

A bottom surface 214 of the syringe 200 may be provided with an opaque coating that may be of color that results in sharp contrast with the syringe contents and syringe plunger to provide additional ease of viewing by the user of the position of the syringe plunger and the plunger/contents interface (demarcation line). The opaque coating may substantially cover the lower half of the barrel, or may include patterns that enhance the user's viewing of the syringe contents and plunger position. For example, an axially extending break may be provided in the opaque coating directly beneath the lumen where the translucency of the syringe barrel allows light to pass to the interior of the lumen from the syringe barrel underside thereby enhancing the user's viewing of the syringe contents and plunger position.

FIGS. 16 and 17 illustrate another alternative configuration for a syringe attachment and syringe. This configuration may be useful for precision dispensing of more viscous syringe contents, such as dermal fillers. In this configuration, the assist feature 1640 may include one or more toothed elements 1642.1 and 1642.2, such as pinion gears formed on the hub of a circular element, such as a wheel, rotatably mounted in the attachment main body in a manner as described above with regard to elements 142 and 144 in FIGS. 1 and 2A. The pinion gears 1642.1 and 1642.2 cooperate with respective geared rack elements 1280.1 and 1280.2 formed on a flat portion 1211 of the syringe barrel 1210. This configuration, as will be recognized, provides a positive actuation (i.e., no slippage) feature for the syringe attachment relative to the syringe. A rubber gripping surface 1644 may enhance the user's ability to rotate the assist feature 1640. Moreover, the assist feature 1640 may be mounted such that it may be free to rotate (i.e., the pinions are not engaged with the racks) in the absence of lateral pressure (downward in FIG. 16 ) on the assist feature. This may be accomplished with spring elements supporting the wheel 1644 within the mounting slots 1614 (FIG. 17 ) on the attachment, or by making the main body of the attachment sufficiently flexible that lateral pressure on the assist feature 1640 causes deformation of the attachment main body and resulting engagement of the pinion gears with the racks. In this manner, inadvertent actuation of the plunger can be avoided. That is, the user must apply lateral pressure to the assist feature before rotating the assist feature in order for syringe contents to be dispensed. The pitch and profiles of the pinion teeth and rack teeth may be designed such that each incremental engagement of a tooth coincides with each gradation on the syringe, or a predetermined volume of dispensed material. Moreover, the profile of the pinion teeth and rack teeth may provide interference, or may include projections or other features that provide tactile and audible feedback to the user, i.e., clicking sensation or sound, which corresponds to a known incremental dispensed volume or to the gradations on the syringe.

Although the present implementations have been described with reference to specific example embodiments, it will be evident that various modifications and changes may be made to these embodiments without departing from the broader spirit and scope of the invention as set forth in the claims. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense. 

What is claimed is:
 1. An attachment for controlling the operation of a syringe, the syringe comprising a barrel and a plunger, the attachment comprising: a main body; a syringe plunger engaging end extending from the main body and adapted to releasably secure the attachment to the syringe plunger; a guide extending from the main body, the guide being adapted to secure the attachment to the syringe barrel while allowing sliding movement of the attachment relative to the syringe barrel; and an assist feature disposed on the attachment between the guide and the syringe plunger engaging end, whereby a user may operate the assist feature to cause sliding movement of the main body and corresponding movement of the plunger relative to the syringe barrel, wherein the assist feature is adapted to provide the user with a mechanical advantage in moving the main body relative to the syringe.
 2. The attachment of claim 1, wherein the assist feature includes a rolling element mounted on the main body and having a friction surface for engaging the syringe barrel.
 3. The attachment of claim 2, wherein the rolling element is mounted to provide selective engagement of the friction surface with the syringe barrel.
 4. The attachment of claim 2, wherein the main body includes at least two mounting stations for the rolling element to permit a user to adjustably mount the rolling element.
 5. The attachment of claim 1, wherein the assist feature includes at least one toothed element.
 6. The attachment of claim 1, further comprising at least one tactile indicator for generating a tactile event to the user as the main body moves relative to the syringe barrel.
 7. The attachment of claim 6, wherein the at least one tactile indicator is a rolling element rotatably mounted on the main body and having a friction surface for engaging the syringe barrel.
 8. The attachment of claim 1, further comprising an optical element mounted on the main body for enhancing visualization of gradations on the syringe barrel.
 9. The attachment of claim 8, wherein the optical element is a magnifying element.
 10. The attachment of claim 8, wherein the optical element includes a bottom flat surface and wherein the main body includes a pair of shoulders for retaining the bottom flat surface a predetermined distance from the syringe barrel.
 11. The attachment of claim 1, wherein the guide includes a U-shaped member for engaging an outer surface of the syringe barrel.
 12. A method of controlling the operation of a syringe, the syringe comprising a barrel and a plunger, the method comprising: providing an attachment having a syringe plunger engaging end, a syringe barrel guide and an assist feature disposed between the syringe barrel guide and the syringe plunger engaging end; inserting the syringe barrel into the syringe barrel guide; releasably engaging the syringe plunger with the syringe plunger engaging end and thereby causing the assist feature to engage the syringe barrel; and operating the assist feature to thereby cause the attachment and the plunger to move relative to the syringe barrel, wherein the step of operating the assist feature comprises rotating a rotatable element on the attachment and frictionally engaging the syringe barrel with the rotatable element.
 13. The method of claim 12, further comprising a step of selecting the rotatable element from a group of different sized rotatable elements and installing the selected rotatable element on the attachment.
 14. The method of claim 12, further comprising a step of adjusting a position of the rotatable element on the attachment.
 15. The method of claim 12, further comprising a step of sensing the position of the attachment relative to the syringe barrel by sensing a tactile event generated by the attachment.
 16. The method of claim 12, the rotating element further comprising at least one pinion gear and wherein the method further comprises moving the at least one pinion gear on a rack on the syringe barrel.
 17. A method of controlling the operation of a syringe, the syringe comprising a barrel and a plunger, the method comprising: providing an attachment having a syringe plunger engaging end, a syringe barrel guide and an assist feature disposed between the syringe barrel guide and the syringe plunger engaging end; inserting the syringe barrel into the syringe barrel guide; releasably engaging the syringe plunger with the syringe plunger engaging end and thereby causing the assist feature to engage the syringe barrel; and operating the assist feature to thereby cause the attachment and the plunger to move relative to the syringe barrel, wherein the step of operating the assist feature comprises operating a rotating element having at least one pinion gear and further comprising moving the at least one pinion gear on a rack on the syringe barrel. 